A man was assaulted in Northampton town centre just before midnight, police have reported.
The 18-year-old victim had left a pub in the Market Square on Wednesday, October 26 and was walking towards Abington Street when a group of about five people approached him.
One of the members of the group walked up to him and slapped him in the face.
They were all in their early 20s and one of them was a man with blonde or ginger hair wearing a blue and yellow light-weight jacket, carrying a black bag.
Anyone with information can contact Northamptonshire Police on 101. Alternatively, they can call the independent charity Crimestoppers anonymously on 0800 555 111.